Diagnoses indicating cancer affecting the anus have been on the rise in recent years. Awareness of this medical issue has increased in kind, with many medical professionals encouraging routine screening for early detection.
The anus is the general term for the opening at the lower end of the intestines, but can informally refer to both the anal opening and the anal canal. The anal canal spans from the rectum to the anal verge, where the canal meets the outer skin of the anus. There are a number of different cell types that make up the rectum, anal canal, and anus. The upper anal canal and some of the nearby rectal tissue comprises tiny column-like cells. Cells near the mid-section of the anal canal are cube-shaped transitional cells. Flat squamous cells comprise the lower anal canal, anal verge, and the perianal skin. Most anal cancers in the United States are squamous cell carcinomas, but anal cancer can also take the form of adenocarcinomas that develop in the cells that line the upper part of the anal canal near the rectum, or in glands located under the inner lining of the anal canal. The presence of anal cancer can show a variety of symptoms including anal bloat, lumps, rectal bleeding, itching, or discharge.
A significant number of anal cancers derive from human papillomavirus (HPV) infections, a sexually transmitted disease. HPV also causes anogenital warts, which can cause anal carcinomas to form. Individuals with a history of anal warts are known to be at risk of developing anal cancer. HPV has also been shown to be a leading cause in cervical cancer in women, and, as such, methods of detection of anal cancer can be seen as counterparts to cervical methods. One such method of detecting cervical cancer is the cervical Pap smear, in which cells are collected from the cervix for analysis to detect cancerous characteristics. Currently, similar methods can be used for cells collected from the rectoanal region to detect anal cancer.
In a typical anal Pap smear procedure, a collection instrument, such as a small brush or a cotton-tipped or DACRON® swab, is inserted into the orifice. The brush or swab is swiped along the surfaces of the orifice tissue to collect a sample of the cells. These collected cells may be suspended in a liquid transport medium after collection, such as a suitable collection and storage fluid used for medical samples. In either case, the collected cells are examined for characteristics indicating cancerous cell growth, generally done by a trained pathologist. In some instances, mechanized examination of the cell samples has automated the initial screening to flag candidates for closer examination. The cell samples may be smeared on a glass slide or remain in suspension for the examination process. The examination process may be by use of imaging, two-sided immunoassay, or any other method of cellular sample examination.
The cell collection portion of a Pap smear procedure can be performed in a doctor's office. However, the procedure itself does not require significant invasive techniques. Thus, the need to visit a doctor specifically for such a procedure is not inherently required, so long as the collection of cells can be done in such a way that the cells are properly collected, preserved, and transported to a pathologist intact for analysis.
While devices relating to cervical Pap smears have been developed and may be applicable to the detection of anal cancer, these kits do not take into account the differences in the structural anatomy between the cervix and the anus/anal canal. One embodiment of the present invention addresses this need by a device specifically for the collection and preservation of cytological cell samples taken from the anus and anal canal.